I love my V1 Printrbot Plus. But I am dazzled by the allure of Dual Extruders. I haven't found any concise descriptions of how to make this happen and I've spent a lot of time researching it. I still have a lot of questions, but I've started down the path very aggressively. This post is an attempt to document my steps to help any other intrepid explorers.

Part 2 of this series documents my conversion to a Bowden tube system for the Printrbot. Part 3 documents the special considerations of getting the Printrbot to dual extrude.

There's more than one way to add dual extruders, but no matter which path is picked there are some significant blocks that have to be overcome. The main one is that the Printrboard simply doesn't support two extruders. There are some clever hacks that come close, but the real way to do it is to replace the Printrboard with a controller that natively supports dual extruders.

Here are the steps that I've planned out. I've gotten past Step 0 and Step 1, but the big ones are still coming.

Additionally, this included tightly calibrating X, Y, Z and E as well as learning how to make the most of the slicing settings of Slic3r. Here are the KISSlicer INI files I'm using:

kisslicer_Deagan.zip

(I'm positive they'll continue to change as I improve.)

Step 1: Bowden Conversion

The weight of a Wade's Extruder on the X-carriage is non-trivial. There is very real inertial momentum that has to be managed when choosing speeds and handling things like the vibration created during rapid short zig-zag fills. The solution to this is to move the extruder off the moving part. The most common way to do this is via a 'Bowden Cable'. This is a tube that connects the stationary extruder to the moving hot end, allowing the filament to be pushed into the hot end from a distance.

Adding a second extruder either means increasing the weight on the carriage or leveraging Bowden cables for two hot ends. I chose the Bowden approach. It's used on a lot of different printer designs and doesn't require trying to constantly optimize the size and weight of two extruders.

For the Bowden tubes and connectors I purchased:- SPC-06-01 Pneumatic Push to Connect Fittings (also sold as Pneufit fittings). This fitting uses a British Standard Pipe Taper Thread R1/8". Tap size is 8.4mm for this thread, but I'm 'self' tapped with the thread itself into the plastic. I used 9.45mm for the base and 9.15 for the tip (it tapers.) I bought these from eBay.

The position of the extruder remains significant. Getting the right mix between tube length and tube bend is important.

It can be placed stand-alone. This is easy but lengthens the tube between the extruder and hot end. Bowden rigs are notorious for 'ooze'. I'd love for others to provide more insight, but my theory is that this is a function of the slight additional length of filament that bends in the tube as the extruder pushes the filament. The bend serves to store potential energy like a spring that continues to force filament into the hot end. The longer the tube, the more stored energy. I created a standalone mount for free standing extruders.

It can be placed to ride on the X-rail. Thingiverse user sponnet has created a [urlhttp://www.thingiverse.com/thing:26963]mount [/url]that lets the extruder ride up and down with the X-axis. This has the advantage of only needing the tube bend to accommodate the back and forth movement of the hot end since the extruder raises and lowers with it. Downside is that it adds weight to the Z-motors, but they're doubled so that may not be an issue.

It can be placed at the top of a Z shaft. This is the mount I created and listed above. This is problematic when the X-axis is homed and the Z-height is very high. That creates a pretty aggressive bend (taunting Lady Friction.) But my PB+ rarely has the Z-axis very high. This has been working very well.

It can be placed somewhere else. Later I intend to create a bridge between the two Z-shafts (adding rigidity,) and mount the extruders up there.

Printing with the Bowden setup has been like starting over from scratch. The 'ooze' issue is huge. I've upgraded to KissSlicer and finally found a set of parameters that leverage the 'suck' function to minimize the ooze. I've been getting greast looking prints again, not quite as good as my stock extruder/hot end arrangement, but very good.

I'm on to Step 2, Replacing the Printrboard with Ramps 1.4 setup. I purchased the Ramps 1.4 boards (Arduino, Ramps shield, Stepper motor shields, LCD Smart controller,) from eBay. It should arrive soon and I'll document the next steps towards dual extruders!What are your experiences with Dual Extruders, Bowden Coversions or Board replacements on the Printrbot?

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Last edited by Tdeagan on 2013-Jul-Sat-15-Jul, edited 1 time in total.

Dual Extruder PB+ Project: Step 1, Bowden Conversion

Im taking the same path but with the plus V2. I ordered RAMPS on ebay as well. I got my bowden extruder setup and im getting the 2nd one ready as we speak. I made a Z axis stiffiner crossbar and it also will serve as a mount for my dual bowden extruders. Ive used RAMPS in the past but it was a long time ago and it was set up for me. Im not sure how to set up the new RAMPS 1.4 with SD card on my PB so, maybe you can be of some help. I POSTED a few pics so you can see what im talking about. My electronics should be here anyday.

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Nice! Positioning the extruders on the cross bar is definitely the way I want to go. It adds stiffness to the Z shafts, it gives good position for the tube bends and it allows for a pretty optimal tube length.

Ya I did a lot of testing before deciding on a final location for the bowden extruder mount. This location or near here is the best. I love this extruder design as well. I have a full write up on my WordPress blog on my signature. For the dual mount I will mount one on the left side of the stiffiner and one on the right.

I also extended my z axis to 16 inches from the top of the bed to the end of the z rods. I lost about 3 inches or less mounting the bowden under the bar instead of on top. This still leaves me plenty of room. Youll have to help me with setting up my ramps if thats ok. Ive done a few mods that work well and you can see them on my WordPress site.

But your custom case is pretty sexy, I've been doing a bit of fiberglassing lately and may have to start thinking about upping my game and doing something fancier.

Luckily it looks like Ramps 1.4 is happy with Pronterface, I've grown accustomed to it and switching slicers has been enough for me on this project. I'll keep careful notes while setting it up and am glad to help any I can!

Last night I printed the ExtrudrPlate - Printrbot Extruder Tray ( v1.7 ) from sponnet and it assembled nicely. I tried it with the hobbed bolt from my stock wooden Wade's Extruder and it worked great. I will note that it was my first encounter with KISSlicer's bridging (which made me miss Slic3r,) and it took a fair amount of effort to sand the raft off all the parts (no way it was 'peeling' off.)

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Now I need to order another hobbed bolt, UBIS Hot End and Kysan NEMA 17 stepper. Printrbot says they'll have hobbed bolts back in stock in a week!

I've decided to buy a matching Kysan NEMA 17. Looking at their specs, they put out a very respectable 76oz-in. I've got quite a few other steppers lying around, but the NEMA 17s I have are all 60-65 oz-in.

I've also decided that the second extruder is going to have an UBIS 1.75mm instead of 3mm Hot End.

I've already got a 3mm, this increases the range of filaments I can use

I really want to do dissolvable support material and I'm very interested in High Impact Polystyrene (HIPS). For the moment, this is only available in 1.75mm, later it'll show up in 3mm, but that will take a while to promulgate among vendors

I want another Ubis, it's a great hot end and I want the height to match between the two (although there are adapters for J-heads.)

Youch, extruders aren't cheap.

Extruder body - okay, I printed that so it's free, right

Vitamins - I have extras of these , but they cost me something once. With the bearings, let's say $10

Kysan with cables - $15

UBIS with cables - $59 + $12 = $71

Toss in shipping and I'm over $100.I'll detail my costs on the Ramps 1.4 in another post, but that and the bowden gear sit right up against $200. So I might get away with a dual extruder upgrade for $325. Given that I opted for the fancy Ramps 1.4 LCD display and other prime parts, that's probably not too bad.

$699 for my original PB+ kit, say another $100 for bed levelers and stabilizers from Printrbot, I'm coming close to $1150 for my dual extruder rig (I'm sure I forgot stuff, so say $1200. Boy am I glad my wife doesn't read this board ) That's a lot cheaper than a Makerbot Replicator at $1899, but surprisingly close to this or this Makerbot knock-off. Of course, I'd never want to have to go wihtout the printrbottalk.com community ...

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Rich's Bowden Geared Extruder for 3mm filament is the one im using now. The black one, and I love it. They make a 1.75mm version as well and if I remember right you have a 6mm od bowden tube which is the same as mine works perfect. My extruder is the best one ive ever had. Thanks so much forr the compliment s on my site. Its much appreciated as I work very hard on my site and improving Printrbot products etc.

Dual extruders in two different filament sizes is a good idea. I have been holding off on doing a Bowden set up since I've been using a lot of Nylon which has oozing issues that I fear would be worse with a bowden. But I do like the flexibility this would give.

Down the road I will be designing a Bowden extruder that will feed 1.75mm and 3mm out of the same extruder. Its the hotend that will make it complicated. Ill prolly cdeate a quick swap mount for changing hotends.

Quick change is rapidly rising on my 'must-have' list. The more I print with the Bowden setup the more I realize that I'd really like to have the the stock extruder available for 'high-quality' prints. I've been considering the Printrbot Plus Quick-Fit Upgrade. My ideal setup would be the dual-extruder bowden rig for multi-color and dissolvable support, but rapid change out for hi-rez. Of course, that requires a third extruder...

Wow. As I type this, it occurs to me that it would be super sweet to have the original 3mm extruder in place with a second 1.75mm bowden driven hot end beside it! Freaky hybrid! Best of both worlds! This will undoubtedly need a new extruder mount to reposition the stock extruder and make room for the bowden hot end. I am so going to start modeling this today!!

It would lose some of the lovely speed advantages that the Bowden conversion has brought me (I'm running better than 50% faster than I was with the stock extruder.) But the majority of my printing is single material parts, so optimizing for that makes sense.

Im about $300-$400 invested in my Printrbot plus but, I did a lot of recycling. My 1st pb original only cost me about $120. I re-used a lot of those parts for this build and I have a healty stock of extra electronic parts laying around at all times. With the modifications I have made on my v2 it is now rock solid. A lot of people think it may be top heavy but it is definitely not. I have also built a locking rail system for my Printrstand that keeps the v2 in place. I have spent extra time on an extensive cooling system for every electronic part involved. That way they will all have a long happy life performing at the best of their abilities.

The Printrstand also makes for a great portable setup as I use it to teach classes to kids. They are always wowed by the abilities and add ons of my Printrbot. Dual extruders will be happening soon as all I need is an extra motor, a few gears and hotend with modified mount. I will be making a few more modifications to the x axis rod mounts, z axis nut mounts, acme rods and the new 1.75mm and 3mm all metal hotends ive designed. The hotends have a very sharp melt zone and can be used in very high temp printing. Also a side note the ubis hotends were originally designed with a triple extruder in mind so they should be a good choice for you.

Did yours come with sd and lcd headers or pins installed? Mine did not. Would you take some quick pics of your ramps board. I also had solder bridging on my 5amp to my 11amp fuse. Make sure you checkk all solder joints before hooking up any board. Mine would of fried if I hadnt checked it first.

I got header pins that I'll need to solder in place for the LCD & aux3. The smart lcd board includes and SD card slot so it apparently makes the sdramps daughter board redundant. I'll inspect carefully for solder bridges, I noticed that a couple of the thru-holes for the LCD are soldered over. The bug yellow F1 fuse is away to high and gets in the way of the fan mount I'm using, so I'll need to desolder it and get it closer to the board. I also had to trim the leads on the bottom of the power input terminals to get it to sit flush on the arduino. Let me know what other shots would be useful.

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There was a 1x18 SIP (for AUX4) and 2x4 DIP (for AUX3) set of pin headers included in the kit. I'll be soldering those onto the board tonight. They're standard 0.1" breakaway style (SIP). Oddly enough, I can't find links on adafruit or sparkfun for the dual row headers. I also didn't find links on the Radio Shack site, so I'm not sure what local options you might have. I'm not sure where I buy them, I almost always pad orders from sparkfun, adafruit, mouser, etc. with stuff like this.

Nice, your a few steps ahead of me when it comes to the dual plus v2. I cant wait to order some new parts. I think eventually ill switch over to kysan motors. I have them on my z axis as of now and im very impressed with them. I found them for a little nit cheepef than pb has them but as long as pb keeps them at $15 I'll order them from them. I want to perfect my single Bowden before I move on to the dual.

.im also taking time to redo all my wiring and label everything. I upgraded all the wire to heavier gauge. I also just ordered over 1, 000 nuts and bolts in variations of sizes as well as 100 different springs. I also upgraded my tool shop with all new tools. So I have to recoup some of that cost and get my ramps all dialed in before dual bowden time. Im glad you got your stuff ordered and im excited to see your setup.

once I covered up the Ramps 1.4 board with a fan, the plugs were a pain to get to

the end stops on the Printrboard use a 3pin plug (with only the two outside pins in use,) whereas the Ramps board uses a 2 pin plug

I really need to look at schematics to verify that the motor wiring is in the same order

the extruder and bed heaters are screw terminals on Ramps and 4 pin plugs on Printrboard

I don't want to make it too difficult to switch back to the Printrboard (at least in the intial phases,) so I soldered up a bunch of headers on a piece of protoboard so that I can use the stock cables currently on the Printrbot and do whatever patches are necessary for the Ramps board.

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This way I can leave the fan in place and still plug/unplug/rewire the connections.

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Hey buddy im finally at the final stages of my dual extruder Printrbot plus. I just need to get my new board which should be here any day now. My other one was DOA. So I thought I would show you what I have so far. I've made some modifications to the standard Printrbot dual extruder beta. Im sure I will need some advise from you for calibration.

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Ya that little extinguisher is perfect for my printer. That way I just put out any fire instead of drowning my Printrbot and room in something that will be a pain to clean up. I also have a full size one for the off chance that it is a major fire.